Kennesaw Corp. common stock is expected to have a return of $13\mathrm{.}2$ percent in a normal economy, $6\mathrm{.}7$ percent in a recession and $24\mathrm{.}5$ percent in a booming economy. In addition, the probability of a normal economy is $74$ percent while the probability of a recessior is $15$ percent, and the probability of a boom is $11$ percent. What is the standard deviation of Kennesav Corp. returns?

$82\mathrm{.}27$ percent

$4\mathrm{.}51$ percent

$7\mathrm{.}48$ percent

$8\mathrm{.}82$ percent